Astronomy:Luyten's Star

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Short description: Star in the constellation Canis Minor

Coordinates: Sky map 07h 27m 24.4991s, +05° 13′ 32.827″

Luyten's Star
Luyten's Star is located in the constellation Canis Minor.
Luyten's Star is located in the constellation Canis Minor.
Luyten's Star
Location of Luyten's Star in the constellation Canis Minor

Observation data
Equinox J2000.0]] (ICRS)
Constellation Canis Minor
Right ascension  07h 27m 24.49897s[1]
Declination +05° 13′ 32.8415″[1]
Apparent magnitude (V) 9.872[2]
Characteristics
Spectral type M3.5V[3]
U−B color index 1.115[2]
B−V color index 1.571[2]
Variable type None
Astrometry
Radial velocity (Rv)17.35±0.19[1] km/s
Proper motion (μ) RA: 571.232[1] mas/yr
Dec.: −3,691.487[1] mas/yr
Parallax (π)264.1269 ± 0.0413[1] mas
Distance12.348 ± 0.002 ly
(3.7861 ± 0.0006 pc)
Absolute magnitude (MV)11.94[2]
Details[4]
Mass0.29 M☉
Radius0.293±0.027 R☉
Luminosity0.0088 L☉
Surface gravity (log g)5[5] cgs
Temperature3,382±49 K
Metallicity [Fe/H]0.09±0.17 dex
Rotation115.6±19.4 d,[6] ~99 d[4]
Age≳8 Gyr
Other designations
Luyten's Star, BD+05 1668, GJ 273, HIP 36208, G 112-17, G 89-19, LFT 527, LHS 33, LTT 12021, NLTT 17881, PLX 1755, TYC 173-3208-1, MCC 17[7]
Database references
SIMBADdata

Luyten's Star /ˈlaɪtənz/[citation needed] (GJ 273) is a red dwarf in the constellation Canis Minor located at a distance of 12.35 light-years (3.79 parsecs) from the Sun. It has a visual magnitude of 9.9, making it too faint to be viewed with the unaided eye. It is named after Willem Jacob Luyten, who, in collaboration with Edwin G. Ebbighausen, first determined its high proper motion in 1935.[8] The star has two confirmed planets and two candidate planets,[4] of which Luyten b is in the circumstellar habitable zone.[9]

Properties

This star is approximately a quarter the mass of the Sun[3] and has 35% of the Sun's radius.[10] Luyten's Star is at the maximum mass at which a red dwarf can be fully convective, which means that most if not all of the star forms an extended convection zone.[11] It has a stellar classification of M3.5V,[3] with the V luminosity class indicating this is a main-sequence star that is generating energy through the thermonuclear fusion of hydrogen at its core. The projected rotation rate of this star[lower-alpha 1] is too low to be measured, but can be no greater than 1 km/s.[12] Measurements of periodic variation in surface activity suggest a leisurely rotation period of roughly 116 days (which would give a velocity of ~0.15 km/s).[6] The effective temperature of the star's outer envelope is a relatively cool 3,150 K, giving the star the characteristic red-orange hue of an M-type star.[5][13]

At present, Luyten's Star is moving away from the Solar System. The closest approach occurred about 13,000 years ago when it came within 3.67 parsecs.[14] The star is currently located 1.2 light years distant from Procyon, which would appear as a visual magnitude −4.5 star in the night sky of Luyten's Star's planets.[15] However, Luyten's Star would only have an apparent magnitude of 4.6 from Procyon's sky because it is much less luminous. The closest encounter between the two stars occurred about 600 years ago when Luyten's Star was at its minimal distance of about 1.12 ly from Procyon.[16] The space velocity components of Luyten's Star are U = +16, V = −66 and W = −17 km/s.[16][17][18]

Planetary system

The Luyten's Star planetary system[4]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
c ≥1.18±0.16 M⊕ 0.036467±0.000002 4.7234±0.0004 0.17+0.13
−0.12 		~72°–90[lower-alpha 2]° —
b ≥2.89+0.27
−0.26 M⊕ 		0.091101+0.000019
−0.000017 		18.6498+0.0059
−0.0052 		0.10+0.09
−0.07 		~72°–90[lower-alpha 2]° —
d (unconfirmed) ≥10.8+3.9
−3.5 M⊕ 		0.712+0.062
−0.076 		413.9+4.3
−5.5 		0.17+0.18
−0.17 		~72°–90° —
e (unconfirmed) ≥9.3+4.3
−3.9 M⊕ 		0.849+0.083
−0.092 		542±16 0.03+0.20
−0.03 		~72°–90° —

In March 2017, two candidate planets were discovered orbiting Luyten's Star.[9] The outer planet, GJ 273b, is a super-Earth in its star's optimistic habitable zone. It has a minimum mass of 2.89 ± 0.26 Earth masses and orbits at a distance of 0.09110 ± 0.00002 AU, completing one orbital period in 18.650 ± 0.006 days. While the planet is on the innermost edge of the star's conservative habitable zone, the incident flux is only 1.06 S🜨, so it may be potentially habitable if water and an atmosphere are present; depending on albedo, its equilibrium temperature could be anywhere between 206 and 293 Kelvin. The inner planet, GJ 273c, is one of the lightest exoplanets detected by radial velocities, with a mass of only 1.18 ± 0.16 Earth masses. However, it orbits much further in, with an orbital period of only 4.7234 ± 0.00004 days.[9]

GJ 273b is one of the closest known planets in its star's habitable zone.[9]

Both planets are near 4:1 resonance; it is possible that, with still undiscovered ones, the entire inner part of this system is trapped in a single simple-mean-motion resonance chain like TRAPPIST-1.

In 2019, two more candidate planets were detected by radial velocity, making a potential total of four known planets in the system.[19] If all four planets are present, their true masses must be close to their minimum masses for the system to be stable, with upper limits of 3.03 M⊕ for b, 1.24 M⊕ for c, 11.35 M⊕ for d, and 9.70 M⊕ for e.[4]

In October 2017, "Sónar Calling GJ273b", a project by METI and the Sónar music festival,[20] transmitted a series of radio signals towards Luyten's star from a radar antenna at Ramfjordmoen, Norway.[21] The signal consisted of a scientific and mathematical tutorial on how to decode the messages and was accompanied by 33 encoded musical compositions by various musicians. A second signal series was transmitted in May 2018. Were anyone listening, the soonest response would be received by 2042.

See also

Notes

  1. ↑ This is denoted by v sin i, where v is the rotational velocity at the equator and i is the inclination to the line of sight.
  2. ↑ 2.0 2.1 In a solution with 2 planets around Luyten's Star for Luyten b and Luyten c, the system was unstable when the inclination was below 50° and the planets were on very eccentric orbits. However, with lower eccentricities, the 2 planet system tolerated the full range of inclinations.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Koen, C.; Kilkenny, D.; van Wyk, F.; Cooper, D.; Marang, F. (July 2002). "UBV(RI)C photometry of Hipparcos red stars". Monthly Notices of the Royal Astronomical Society 334 (1): 20–38. doi:10.1046/j.1365-8711.2002.05403.x. Bibcode: 2002MNRAS.334...20K. 
  3. ↑ 3.0 3.1 3.2 The One Hundred Nearest Stars (Report). Research Consortium On Nearby Stars. 2009-01-01. http://www.astro.gsu.edu/RECONS/TOP100.posted.htm. Retrieved 2009-09-03. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Pozuelos, Francisco J.; Suárez, Juan C.; de Elía, Gonzalo C.; Berdiñas, Zaira M.; Bonfanti, Andrea; Dugaro, Agustín et al. (2020). "GJ 273: On the formation, dynamical evolution, and habitability of a planetary system hosted by an M dwarf at 3.75 parsec". Astronomy & Astrophysics 641: A23. doi:10.1051/0004-6361/202038047. Bibcode: 2020A&A...641A..23P. "GJ 273 is a planetary system orbiting an M dwarf only 3.75 pc away, composed of two confirmed planets, GJ 273b and GJ 273c, and two promising candidates, GJ 273d and GJ 273e ... the system remained stable only for values of inclinations ranging from 90◦ to ~72◦". 
  5. ↑ 5.0 5.1 Viti, S.; Jones, H. R. A.; Richter, M. J.; Barber, R. J.; Tennyson, J.; Lacy, J. H. (August 2008). "A potential new method for determining the temperature of cool stars". Monthly Notices of the Royal Astronomical Society 388 (3): 1305–1313. doi:10.1111/j.1365-2966.2008.13489.x. Bibcode: 2008MNRAS.388.1305V. 
  6. ↑ 6.0 6.1 Suárez Mascareño, A.; Rebolo, R.; González Hernández, J. I.; Esposito, M. (September 2015), "Rotation periods of late-type dwarf stars from time series high-resolution spectroscopy of chromospheric indicators", Monthly Notices of the Royal Astronomical Society 452 (3): 2745–2756, doi:10.1093/mnras/stv1441, Bibcode: 2015MNRAS.452.2745S 
  7. ↑ "BD+05 1668". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BD%2B05+1668. 
  8. ↑ Luyten, W. J.; Ebbighausen, E. G. (September 1935). "A faint star of large proper motion". Harvard College Observatory Bulletin 900 (900): 1–3. Bibcode: 1935BHarO.900....1L. 
  9. ↑ 9.0 9.1 9.2 9.3 Astudillo-Defru, Nicola; Forveille, Thierry; Bonfils, Xavier; Ségransan, Damien; Bouchy, François; Delfosse, Xavier et al. (2017). "The HARPS search for southern extra-solar planets. XLI. A dozen planets around the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628, and GJ 3293". Astronomy and Astrophysics 602: A88. doi:10.1051/0004-6361/201630153. Bibcode: 2017A&A...602A..88A. https://www.aanda.org/articles/aa/full_html/2017/06/aa30153-16/aa30153-16.html. 
  10. ↑ Lacy, C. H. (August 1977). "Radii of nearby stars: An application of the Barnes-Evans relation". Astrophysical Journal Supplement Series 34: 479–492. doi:10.1086/190459. Bibcode: 1977ApJS...34..479L. 
  11. ↑ Reiners, Ansgar; Basri, Gibor (March 2009). "On the magnetic topology of partially and fully convective stars". Astronomy and Astrophysics 496 (3): 787–790. doi:10.1051/0004-6361:200811450. Bibcode: 2009A&A...496..787R. 
  12. ↑ Reiners, Ansgar (May 2007). "The narrowest M-dwarf line profiles and the rotation-activity connection at very slow rotation". Astronomy and Astrophysics 467 (1): 259–268. doi:10.1051/0004-6361:20066991. Bibcode: 2007A&A...467..259R. 
  13. ↑ "The Colour of Stars". Commonwealth Scientific and Industrial Research Organisation. 21 December 2004. http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html. 
  14. ↑ García-Sánchez, J. (2001). "Stellar encounters with the solar system". Astronomy and Astrophysics 379 (2): 634–659. doi:10.1051/0004-6361:20011330. Bibcode: 2001A&A...379..634G. http://www.aanda.org/articles/aa/pdf/2001/44/aah2819.pdf. 
  15. ↑ Schaaf, Fred (2008). The Brightest Stars: Discovering the universe through the sky's most brilliant stars. John Wiley and Sons. p. 169. ISBN 978-0-471-70410-2. 
  16. ↑ 16.0 16.1 "Annotations on LHS 33 object". SIMBAD. Centre de Données astronomiques de Strasbourg. http://cdsannotations.u-strasbg.fr/annotations/simbadObject/971564. 
  17. ↑ Delfosse, Xavier; Forveille, Thierry; Perrier, Christian; Mayor, Michel (March 1998). "Rotation and chromospheric activity in field M dwarfs". Astronomy and Astrophysics 331: 581–595. Bibcode: 1998A&A...331..581D. 
  18. ↑ "ARICNS star page of GJ 273". Astronomisches Rechen-Institut Heidelberg. http://www.ari.uni-heidelberg.de/datenbanken/aricns/cnspages/4c00562.htm. 
  19. ↑ Tuomi, M.; Jones, H. R. A.; Anglada-Escudé, G.; Butler, R. P.; Arriagada, P.; Vogt, S. S.; et al. (2019). "Frequency of planets orbiting M dwarfs in the Solar neighbourhood". arXiv:1906.04644 [astro-ph.EP].
  20. ↑ "Sónar music festival". https://sonar.es/. 
  21. ↑ "How to send a message to another planet". The Economist. 16 November 2017. https://www.economist.com/news/science-and-technology/21731380-including-clock-some-trigonometry-and-some-jean-michel-jarre-how-send/. Retrieved 19 November 2017. 

External links



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